A plugin owning a standalone open/close bracket cannot tell a dead marker
from a live one: an unmatched `compact/start` reads identically whether the
previous writer died mid-compaction or a compaction is running now.
`Session.firstLiveSeq` already holds that answer exactly, but only in memory.
Append the log-only `session/inherited` event at that seq from the seeded
constructor — the single waist all six seeded-start paths pass through
(resume, configured startup on a persisted id, `sessions.fork()`, a subagent
fork child, `adopt()`'s live prefix, and a bare seeded `create`). Read it
through the new `isInheritedSeq(events, seq)`.
The constructor placement means persistence needs no changes: the marker is
already in `events` when a backend captures the creation seed, so it rides
the ordinary seed path with no load-time write. It also covers fork, where
the inherited bracket's owner may still be running — the case a
persistence-layer boundary could not reach.
Activity ordering excludes the boundary through `lastActivityTime()`, since
lazy resume makes browsing a pickup and the three call sites would otherwise
float every opened session to the top of a picker or list.
SessionTitleInvalidError narrows the one rename failure that blames the
input; the fallback-unpin append extracts to appendFallback beside
ensureFallback's guarded twin; a deferred-provider test proves rename
supersedes ACTIVE generation; the invariant companion enforces
messageSeqs-empty iff user-source on every appended session/title event
(tsconfig gains the session-title invariant path); SessionTitleEventData
field docs state the third source kind and the empty-seqs rule, mirrored
into the bilingual core-data-structures page; the note qualifies the
refresh unpin as conditional on a derivable replacement.
The default arm of copySessionTitleSource is a closed-union exhaustiveness
guard (compile-time protection for the next kind); it is unreachable at
runtime, so the per-file coverage gate ignores it like every other
assertNever arm.
sessionTitle.rename appends a user-source session/title event; onUserMessage
skips scheduling while a user title stands, and an explicit refresh is the
deliberate unpin (provider regeneration, or a re-derived fallback when no
provider is registered).
The consumer-side restated declare-merges retire (user ruling: one home per
projection key): TodoPanel imports the todos merge and TodoItem through
@deepseek-ai/dsh-tool-todo/client, and the manager takes the title merge
through @deepseek-ai/dsh-session-title/client — both pure-type outlets
re-exporting the domain's single-source types.ts, so no host value import or
Context merge enters the client program (type-only edges, exempt from the
plugin value-import ban). Workspace deps and tsconfig references added.
Also aligns the fixture's empty-log tail block with the host convention
(asOfSeq -1 with empty values, block always present on tail requests).
